Definition: In this task, you are given an input list A comprising of numbers and alphabets. You need to extract and sort the unique alphabets in the list. The alphabets in the input list will only be in lowercase. Return -1 if there is no alphabet in the input list.
Input: ['k', 'l', '2275', '7983', 'd', 'q', 'e', 'c', '6185', '4875']

c, d, e, k, l, q